This project is directed toward the detection of functional changes in the cardiovascular system associated with compounds of environmental significant to which toxicologically significant exposure would be expected by inhalation. Carbon disulfide-present in perfusate at concentrations as low as 100 ppm (v/v) has caused contracture in isolated, perfused rabbit hearts under certain experimental conditions. A series of experiments is underway to verify and characterize this phenomenon more fully and, if possible, determine the physiological mechanism of action.